Luminair



05115, 1929. -w. A1 -R'EY 1,731,714

wulm'a- Filed June 36?."' 1928 a 2 Shouts-Sheet 1 INVENTOR AATTORNEY I Patented Oct. 15, 1929 UNITED STATES PATENT OFFICE a. DOREY. or NEWARK, onro, assrenon. 'ro HOLOPHANE comm, ma,

. or new YORK, N. Y., A conrona'rxon on NEW YORK LUMINAIB Application Vflled June 26,

The object of this invention is to construct a I'uminai'r provided with a combination of light' retracting surfaces which will distribute light with reasonable uniformity over the 8 vertical surfaces of books arranged in stacks j; at each side of a narrow aisle the light sources being mounted overhead at the centre of the aisle and at the level of the top shelf of the stacks;

10 In all libraries it is important that storage space he e'conomized to the greatest degree consistent with convenience in reading the book titles when they are in place, removing the books from any of the shelves, examining them when they are removed; and sufiicient head room allowance to permit a tall' adult to pass down or stand in any part of the aisle in comfort. This has led to a close standard- Th izat ion'of all dimensions in book spaces with strict reference'to the size of a large adult.

It has been found that the aisles between book stacks vary little in width from an average of three feet, that the height of the stack tiers from floor to ceiling varies little from seven and one half feet and that the shelving is contiliuous from floorto ceilin The normal l ocation of lig t sources is overhead and'in the central line of the aisles. If y the light sources are spaced very widely apart it will be impossible to furnish adequate illumination on the books midway between the sources on account of the glancing angle and the distance, unless a very high intensity be projected in such directions. In that case the 85 angle at which high intensities are delivered is so close to the line of sight of an individual walking down the aisles that the fringe of the light beam will cause a very serious glare -condition. If the light sources are spaced 40 very closely all of the cost elements in the installation will be unduly high. It hasbeen found that an average spacing of six feet is a good practical compromise between these. limitations. Y Fig. 1 is an elevation of my invention as Fig. 5 is a diagonal vertical crosssection of Fig. 2, and Fig. 6 is a diagonal vertical cross section of Fig. 2 taken at a more acute angle with the cente'rline of the aisle than Fig'. 5.

In Fig. 1, 7 is a lightsource shown for convenience as a point at the optical centre of the light giving element in the lamp vbulb 8.

e source is surrounded by a compound enclosure 9 consisting ofatop reflecting member 10 and a bottom transmitting and rte- 5 fracting bowl 11. The reflector 10 includes the upward light emitted by. the source and p is preferably of crystal glass and provided on its'exterior surface with double reflecting prisms 12. The'contour of reflector 10,is slightly ellipsoidal so that the reflected rays are returned to the bowl part 11 at slight angles with the downward light raysdirect from the source. The effect of such reflected rays is to reinforce the downward intensity of the light and increase the diffusion of the light or blur the source jvithout increasing the total angle of light delivered at any point on the bowl beyond the limits of eflicienttransmission. The outer surface of the ,bowl 'll is provided with prisms 13 which are v.concen tric on the vertical axis of the unit'14'14. Themajor portionof these prisms are adapted to concentrate the light downward toward 85 the axis of the bowl 14 -14.- Near the top edge of the bowl the inclinationofthe iefracting faces is gradually reduced so that a small portion of the light rays will be emitted at high angles with-the horizontal as the limit, 90

so that suflicient illumination may be delivered to the upper shelves.

In Figs. 1 and 2 the bowl 11 is provided with a plurality of refracting systems which are symmetrical in design and operation with reference to the transverse vertical plane 1-1 through the source and also the longitudinal vertical plane 15-15 through thesource. The construction of any one quadrant is therefore typical of all four quadrants. The arrangements of these retracting systems is best explained by reference to the typical installation diagrams Figs. 3, 4, 5 and 6 in their relation to Fig. 2. Vertical plane 4-4: in Fig. 3 passes through the enclosure 9 and is normal to the book stacks. Cross section in this plane is shown inFig. 4. Vertical plane 5-5 in Fig. 3 passes through series of prisms parallel to this intercept;

, The prisms centre upon the plane 16-16 and are adapted to concentrate light in a wide wedge toward that plane while the outer prisms 13 opposed thereto act in combination with the inner prism to complete the concentration toward the plane 16-16 and reduce somewhat the lateral spread of the beam wedge. In Fig. 2 the intercept of the vertical diagonal plane 5-5 lies within the refracting system 18 and the refracting system itself consists of a series of prisms parallel to the plane 5-5. The prisms centre upon the plane 5-5 and are adapted to concentrate light-in a wide wedge toward that plane while the outer prisms 9 opposed thereto act to redistribute the light downward along the long axis of the wedge so that the intensities are greatly built up as the intercept of the floor and book stack is approached.'- To simplify the theoretical design it would be desirable that system 18 Fig. 2

should cover all of the interior surface of the quadrant of bowl 11 which is not occupied by system 17. If that were done, however, an undue proportion ofthe refracting surfaceswould have to besacrificed in order that the plunger which forms the interior surface of the bowl might relieve from the glass at the end of the pressing operation.

I have, therefore, introduced a third refract- The outer prisms 13 opposed thereto act to redistribute the light in downward directions. The transverse or inward spill from the wedge beam centering on plane 5-5 laps the upward and outward spill from the wedge beam centering on slanting plane 16-16 and these are lapped by the longitudinal or outward spill from the corresponding wedge beam from the next adjacent unit centering on the plane corresponding to plane 5-5. These three components combine to, give a substantially uniform illumination on the unit vertical surface of the book stack included between plane 4-4, plane 5-5, floor and ceiling.

In Fig, 4, 20 indicates the-relative distribution of intensity in plane 4-4. In Fig.

5, 21 indicates the relative distribution of intensity in plane 5-5. In Fi 6, 22 indicates the relative distribution 0 intensity in plane 6-6. The distribution in the vertical plane through the centre of the aisle 15-15 Fig. 3 is very similar to 22 in Fig. 6. The

highest illumination on the vertical book stacks produced by these distributions is at the top shelf Fig. 4.. The lowest illumination is at the intercept .of the slanting plane 16-16, Fig. 4 and Fig. 5.

Owing to the general form of light distribution, a very good reading light is obtained at any point in the aisle. Owing to installation conditions glare 'is negligible when the user is looking at the book stacks. When one is passing along the aisle glare is reduced to a very low degree on account of the relatively concentrating form of distribution which gives very low intensities at high angles in the field of view.

While I have shown and described a device using a single transmitting bowl I do not conceive my invention to be limited to that form. It is evident that a double glass transmitting'bowl can be used consisting of an inner bowl with smooth inner surface and provided with concentric prisms on the outer surface and an outer bowl with smooth outer surface and the arrangement of various refracting systems on its interior surface. .The prismatic design of such a combination would be entirely similar in kind to that of the single bowl. The total output would be decreased on account of the two layers of trans mitting glass but the limits of control would be increased because two additional surfaces are introduced.

It is evident also that the material used in making the ripper reflecting part of the enclosure and the contour of the samemay be changed materially without affecting the essential principles of my invention. The invention has been described with special reference to book stacks or library aisles but it is evident that it can be applied to any confined aisle spaces and illumination layouts involving similar conditions.

I claim: v 1. A luminair for library stack room lighting, comprising a light source, a reflecting cover and a retracting bowl, the bowl having on one surface a series of annular retracting prisms concentric on the vertical axis of the luminair and adapted to redirect the light so that intensities toward the vertical are greatly increased and intensities toward the horizontal are greatly decreased and opposed thereto a series of cooperating retracting systems I adapted to concentrate light toward certain library book stacks, comprising a plurality of luminaires stationed at convenient inter vals in a line between adjacent stacks, eachluminair'consisting of a reflecting cover and a lower refracting bowl divided into a pluralit of retracting systems, the optical axes of w ich intersect respectively the book stacks in vertical planes midwa between the stations and the floor line of t e book stacks.

Signed at Newark, in the county of Licking and State of Ohio, this 22nd day of June,

WILLIAM A. DOREY- in the surface of the stacks widely spaced on each side of the 'luminair.

3. A luminair for library stack room lighting, comprising a light source, a reflecting cover and a retracting bowl, the bowl being divided into a plurality of retracting systems, the optical axes of which intersect the surface of the stacks respectively at the floor line and in vertical lines'widely spaced on each side of the luminair.'

4. A luminair for library stackroom light ing, com rising a light source, a reflecting cover an a retracting bowl, the bowl having .on' one surface annular retracting prisms adapted to redirect the light in generally downward directions and opposed thereto a series of cooperating refracting systems adapted to concentrate the light toward the floor line of the stacks and toward vertical lines in the surface of the stacks widely spaced on each side of the luminair.

5. A luminair for library stack room light- 7 ing, comprising alight source, a reflecting cover and a retracting bowl, the bowl having on one surface annular retracting prisms adapted to redirect the light in generally downward directions'and opposed thereto a series of cooperating retracting systems adapted to concentrate light toward the floor line of the stacks and toward vertical lines in the surface of the stacks widely spaced on each side of the luminair.

6. A luminair for library stack room lighting having a reflecting cover and a retracting bowl, the outer surface of which is provided with annular prisms, and the interior surface divided into a plurality of systems of parallel prisms, the optical axes of the different systerns being at definite angles with each other.

7. A system of illumination for lighting 

